This application claims priority from German Application No. 101 15 767.3-21 filed Mar. 29, 2001, from European Patent Application No. 02001780.2 filed on Jan. 25, 2002 and from European Patent Application 02002159.8 filed on Jan. 29, 2002.
1. Field of the Invention
The invention relates to a joint between two vehicles or vehicle parts such as an articulated bus or a railcar for example.
2. Description of the Prior Art
Joints between two vehicles or vehicle parts, in an articulated bus for example, are notoriously well known. A central joint in the form of a buckle joint is thereby provided, its central axle being arranged in the central longitudinal axis of the vehicle. The vehicle buckles about this axle when threading a curve.
The shortcoming of the known buckle joints is that the two vehicles or vehicle parts need to be separated by a distance of approximately 1,600 mm on account of the extension of the joint. As the space the joint occupies between the two vehicles or vehicle parts is in principle of limited use only, there is an interest in minimizing the distance between the two vehicles or vehicle parts in order to possibly accommodate another row of seats in the vehicles or vehicle parts.
The object of the invention is therefore to provide a joint, more specifically a buckle joint, that permits to reduce the distance between the two vehicles or vehicle parts that are joined together by way of said joint as compared to a conventional buckle joint.
To achieve this object and in accordance with the purpose of the invention, a first variant suggests to provide the joint with at least two joint members that are held apart from the central longitudinal axis of the vehicle and with at least one, preferably two joint arms that is/are carried so as to be capable of rotating about the two joint members. In the simplest case i.e., in an embodiment with two joint members and one joint arm, the joint arm, depending on the direction of the curve, alternatively rotates about the axle of the one or of the other joint member in a way similar to that of a swinging door. It has thereby to be made certain that the respective one of the joint members that is not in operation is fixed.
In dividing a central buckle joint into two joint members which have one pivot each and are located outside the central longitudinal axis of the vehicle i.e., to the side of the vehicle, the distance between the two vehicles or vehicle parts in the region of the joint is reduced. More specifically, the distance of heretofore 1,600 mm may be reduced to less than 1,100 mm, so that another row of seats may be arranged in one of the vehicles or vehicle parts. Another advantage is that the bellows may be shortened to about half its length due to the reduced distance between the vehicles, which is particularly advantageous with regard to cost since the central frame that serves as a stabilizing element may be dispensed with. Another advantage is that the change in the kinematics that was occasioned by the division into two joint members causes the bellows to be only slightly displaced transversely, which results in an improved durability of the bellows. From a constructional point of view, splitting the prior art central buckle joint into two joint members that are held apart from the central longitudinal axis of the vehicle causes the one or the other joint to be activated depending on the curve the vehicle has to thread. By virtue of the reduced length when traveling around a curve, the bellows bulges less, more particularly downward, because it may be of a more rigid configuration as it is only slightly displaced transversely. Inasmuch, busses with little road clearance (low-platform busses) may also be built with such a joint or bellows.
Further advantageous embodiments and features of this variant will become apparent in the subordinate claims.
In a first embodiment with two joint arms, it is for example particularly advantageous that each vehicle or vehicle part be provided with a bearing bracket, each of the bearing brackets receiving a joint arm. Said joint arm is thereby rotatably connected to the bearing bracket. To attach the joint to the vehicle by means of bearing brackets has the advantage that the joint may be inserted between the two vehicles or vehicle parts as an entity so to speak.
Furthermore, the bearing brackets are advantageously flush on the vehicles or vehicle parts i.e., they are arranged on the same height in an effort to prevent vertical moments from being brought into the vehicles or vehicle parts.
To minimize the height of the joint as a whole, the two joint arms are arranged, according to another feature, above and beneath the corresponding bearing bracket.
To prevent the joint from not being activated when the vehicle is traveling in a straight line, the two joint arms are non-rotatably linked to the corresponding bearing bracket in the joint member in the region of their respective pivot. This also means that, when threading a curve, the corresponding joint arms are alternatively rotatably linked to the one or to the other bearing bracket, stopping or locking of the respective one of the joint members depending on the curve that has to be threaded. More specifically and to prevent rotation, at least one bolt is provided for connecting at least one joint member to the respective one of the bearing brackets.
As the two joint arms are joined together, the bolt must take hold of both the one and the other joint member in order to fixate the one joint in such a manner that it cannot rotate.
According to another advantageous feature, the one bearing bracket may be linked to the vehicle or vehicle part in such a manner as to be vertically pivotal which permits the vehicle to travel through depressions or drive over hilltops.
According to a second and third embodiment, the solution in accordance with the invention is that the joint members that are held apart from the central longitudinal axis of the vehicle may be slidably received by the one vehicle or vehicle part across the central longitudinal axis of the vehicle, the two joint arms being connected by their other end to the other vehicle or vehicle part by means of a swivel joint that is arranged in the central longitudinal axis of the vehicle. This clearly shows that the buckling movement is performed in two stages. On the one hand the connection of the joint members to the other vehicle or vehicle part by means of a swivel joint arranged in the central longitudinal axis permits a certain buckling angle, preferably a buckling angle of up to 15xc2x0. If the buckling angle needs to be higher, which is for example the case when such a bus must travel around sharp curves, one of the joint members is displaced across the central longitudinal axis of the vehicle, thus enlarging the buckling angle. For, depending on the curve that is threaded, the one joint member, with a vertically oriented axle for example, that holds the one joint arm is caused to move toward the other joint member with the other joint arm. The joint arm hereby oscillates about the corresponding joint member. This means that the distance between the two vehicles or vehicle parts increases on the outer side of the curve, the extent of the increase of said distance between the two vehicles or vehicle parts being dimensioned in function of the capability of the joint member that holds the joint arm of moving toward the other joint arm. How much the distance between the two vehicles or vehicle parts increases additionally depends on the length of the joint arms.
This buckling in two stages bases on the finding that in 90% of the driving time of an articulated bus the maximum buckling angle to be realized is of only 15xc2x0. Merely exceptional cases require greater buckling angles and it was found out that buckling angles never exceed 26xc2x0. The angle of 26xc2x0 also corresponds, by the way, to the maximum buckling angle of a prior art joint.
It was found that the distance between the two vehicles or vehicle parts can also be reduced from originally 1,600 mm to less than 1,100 mm by virtue of this special construction of the joint. The length of the built-in bellows only amounts to about 800 mm. As a result thereof, another row of seats may be arranged in one of the vehicles or vehicle parts.
It is well known to provide the region of the joint with a connection that permits the passage from one vehicle to the other. The connection is comprised of an intercar gangway and of a bellows that surrounds both the gangway and the joint in the manner of a tunnel.
The advantages regarding design and durability of the bellows as they have been described for the first variant apply to these variants as well. More specifically, the bellows is shortened. By virtue of the buckling kinematics, the bellows is displaced in transverse direction but slightly, which positively influences its durability. As the bellows is only slightly displaced transversely, it may be made stiffer so that it bulges less, more particularly in downward direction.
Further advantageous features of the second and third embodiments will become apparent in the subordinate claims 11 through 24.
According to a particularly advantageous feature, the respective joint members for joint arms are arranged on a cradle that is movable across the central longitudinal axis of the vehicle. The cradle is thereby advantageously arranged on a bracket guiding device, in this case more specifically on a bracket guiding device provided with a round guiding facility, said bracket guiding device being connected to the one vehicle or vehicle part. The advantage of a such type bracket guiding device with a round guiding facility is that the cradle may be received by the bracket guiding device in such a manner that it may be pivoted vertically, the joint as a whole being, as a result thereof, capable of yielding to nodding movements as they occur for example when such type articulated vehicles travel through a depression or drive over a hilltop.
A bracket for the swivel joint is provided on the other vehicle or vehicle part, said swivel joint serving to receive the joint arms in such a manner that they are pivotal.
To attenuate the motion of rotation of the joint arms about the swivel joint, an attenuating device is provided. A such type attenuating device includes at least one attenuator that is connected on the one hand to the joint arm and on the other hand to the vehicle or vehicle part or the bracket. It is the function of such an attenuator, which is preferably realized as a double acting attenuator, to for example prevent the rear vehicle part when the vehicle of concern is a so-called pusher vehicle i.e., a vehicle in which the last rear axle is driven, from swerving to the side when the vehicle is traveling in a straight line. Furthermore, the bracket or the joint arm is advantageously configured in such a manner that the attenuator plunges into the bracket or the joint arm when the joint executes a pivoting movement, the whole buckling angle being thus available.
According to another feature of the invention, an attenuating member is advantageously provided between cradle and joint arm (second embodiment). Alternatively, an attenuating member may be arranged between the joint arms or, even better, between the cradles (third embodiment). Since, in arranging one respective attenuating member between cradle and joint arm, a total of two such attenuating members is required, the embodiment with one double-acting attenuating member located between the cradles or the joint arms respectively is less expensive. The primary function of said attenuating members or member is to allow the second stage of buckling to only happen when the swivel joint has reached the 15xc2x0 limit of the buckling angle, which constitutes the first stage. Up to the buckling angle of 15xc2x0, the cradles are stopped in their position by the attenuating member or members respectively. Upon reaching the buckling angle of 15xc2x0, the attenuating member or members soften; as a result thereof and in function of the curve to be threaded, the respective one of the cradles moves on the bracket guiding device toward the other cradle. Although the attenuating member or members respectively develop a certain, though small attenuating effect at a buckling angle of more than 15xc2x0 as well, the major part of the attenuation is performed by that attenuator that is active, which depends on the direction of the curve. This is the attenuator that is located on the outer side of the curve.
As already described herein above, the bracket guiding device may be realized as a round guiding facility so that the cradle, which is received by the round guiding facility, is vertically pivotal. In order to alternatively be capable of yielding to such nodding movements, the bracket on the other vehicle may be designed in such a manner that it is pivotal about a horizontal axle. In such a case, the bracket guiding device for the cradle could also be fixed in vertical direction. Bracket guiding device and bracket may also concurrently form the transverse beam of the vehicle""s or the vehicle part""s chassis, which permits to spare weight on the one hand and costs on the other.
In order to be capable of absorbing smaller swaying movements the cradle is advantageously provided with an elastic guide bush for receipt through the round guiding facility.
According to a second variant, a joint is provided between two vehicles or between two vehicle parts, of an articulated bus or a railcar for example, said joint being provided with a pivot bearing that connects the two vehicles or vehicle parts, said vehicles or vehicle parts slidably receiving said pivot bearing across the longitudinal axis of the vehicles or vehicle parts. In exactly the same manner than with the embodiments of the first variant, this construction permits to realize a short bellows with all of the advantages that have already been described with respect to the first variant and its embodiments. The important point in this variant is again that from a certain buckling angle, namely from a buckling angle of more than 15xc2x0, the pivot point is displaced across the central longitudinal axis i.e., toward the outer side of the vehicle or of the vehicle parts respectively. That is to say, up to a buckling angle of 15xc2x0 the pivot bearing operates like a normal joint and does not change its position in the central longitudinal axis of the vehicle. Not before a buckling angle of more than 15xc2x0 does said pivot bearing move toward the one or the other outer side of the vehicle, depending on the curve to be threaded.
In this connection there is more specifically provided that each vehicle or vehicle part be provided with a guidance for the pivot bearing. The guidance may hereby be configured as a bracket that extends across the central longitudinal axis, said pivot bearing being provided on either side with one cradle that is slidably received by the bracket.
In order to make certain that the pivot bearing is not displaced before a buckling angle of 15xc2x0 is reached, the bracket is provided with an attenuating device that is connected to the pivot bearing. This clearly shows that the attenuating device is rigid up to a buckling angle of 15xc2x0 so that the pivot bearing is fixed in its position in the central longitudinal axis of the vehicle, and only softens when the buckling angle exceeds 15xc2x0 so that the pivot bearing moves outward on the bracket in an effort to provide the required higher buckling angle.
In order to make certain that a vehicle fitted with such a joint is capable of driving over hilltops and traveling through depressions, there is provided that at least one bracket be arranged on the vehicle or vehicle part in such a manner that it is pivotal about a horizontal axle.
To limit the buckling angle, a stop is provided between the brackets in spaced relationship from the central longitudinal axis, said stop advantageously providing guiding functions. This means that, by virtue of its construction and more specifically with regard to the design of the stop, said joint is also capable of absorbing swaying movements. To this purpose, the stop is more specifically comprised of two arms, each arm being arranged on a respective one of the brackets and both arms being configured in the shape of a fork and being slidable into one another. Accordingly, when a vehicle fitted with a such type joint is traveling in a straight line, the two arms of the stop are guided one into the other, the outer pair of arms losing contact with each other only when the vehicle travels round a curve while the other pair of arms, namely that pair of arms that is located on the inner side of the curve, is kept in contact and is capable of absorbing swaying movements.
The subject matter of the invention also is an articulated vehicle such as an articulated bus or a railcar for example, the various vehicle parts of which are linked together by means of a joint, said joint being characterized by one or several features of the two variants or of the embodiments described herein above.
The two variants of the invention with their embodiments will become apparent from the following detailed description of the invention and accompanying drawings.